1. Field of Invention
This invention relates to tire building and especially centering and placing a circular tire bead on a bead setter for application to a tire carcass built on a tire building drum.
2. Description of the Related Art
In the building of a tire, a bead or bead apex assembly is fabricated at a position away from the tire building drum and then applied to the plies which have been positioned on the tire building drum during revolutions of the drum. At the time the bead or bead apex assembly is applied to the tire casing which has been built on the drum, it is important that the beads be set in a cylindrical configuration and in a centered position relative to the cylindrical drum on which the carcass is built. It has been found that this operation cannot be done manually with the necessary precision and therefore a tire bead holder is needed for gripping the circular tire bead and placing the bead in a circular condition at a concentric position on a bead setter. The bead is held on the bead setter by magnets in the position it is received and is then carried to the tire building drum where it is applied to the tire carcass. In U.S. Pat. No. 4,726,861 a tire bead centering and feeding apparatus is proposed where the beads are supported and centered on hinged arms having bead supporting fingers which engage the bead as the hinged arms are moved about a swinging axis. The movement of the hinged arms causes the fingers to be applied unevenly which may result in deviations in the centering of the bead.
The present invention is directed to an improved tire bead holder assembly in which the bead holding fingers are moved simultaneously and equally in a radial direction to center and hold the bead or bead apex assembly. A direct drive chain is connected to radially moveable slides for supporting the fingers providing substantially equal centering forces on circumferentially spaced portions of the bead. A simple piston cylinder assembly connected to the chain drive provides the simultaneous movement of the fingers.
In accordance with one aspect of the invention, there is provided a tire bead holder assembly for gripping a circular tire bead and placing the bead in a concentric position on a bead setter comprising a supporting disk, a plurality of circumferentially spaced radially extending linear guide members on the disk characterized by slide members mounted on each of the guide members, each of the slide members having an axially extending bead holding finger for engaging the bead and a radially moveable drive means in engagement with each of the slide members for moving each of the slide members and each axially extending finger radially into and out of engagement with the tire bead.
In accordance with another aspect of the invention, there is provided a method of holding and positioning a tire bead for transfer to a bead setter from a bead holder comprising:
a. placing the bead over a plurality of circumferentially spaced fingers mounted on radially moveable slide members;
b. moving said slide members with a chain adjacent and attached to each of the slide members to provide simultaneous radially outward movement of each of the fingers into centering and gripping engagement with the bead.
c. applying pressure by the fingers on the bead with the forces from the chain applied by a piston cylinder assembly;
d. moving the fingers into an opening in the bead setter providing for engagement of the bead with the bead setter in a centered position;
e. applying a retaining force on the bead by the bead setter;
f. releasing the bead by moving the fingers radially inward; and,
g. retracting the bead holder from the bead setter;
Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.